AQA A-level Biology paper 1
A vaccine can be used to produce immunity. Describe how memory cells are important in this
process. (3) - correct answerimportant because when individual is in contact with virus again,
antibodies can be produced at a faster rate in a secondary immune response, and so the
pathogen can be destroyed faster.
abiotic - correct answernon-living
artery structure - correct answerthick muscle layer so that they can dilate and contract to
smooth blood flow.
thick elastic layer so artery can stretch and recoil with systole and diastole, smoothing blood
flow.
overall thickness of wall is large so that it doesn't burst under pressure.
artificial active immunity - correct answerinvolves inducing an immune response in an individual
WITHOUT them suffering the symptoms of the disease.
e.g. vaccinations
memory cells produced
Attaching lactase to the beads is a more efficient use of lactase than adding the lactase
directly to cow's milk.
Suggest three reasons why it is more efficient to attach lactase to the beads. - correct
answerlactase bead can be reused
continuous process
lactase not present in milk
,before cell fractionation, why is the tissue placed in a cold, isotonic buffer? - correct answercold:
reduce enzyme activity that may break down the organelles
isotonic: same water potential as tissue, this prevents organelles shrinking/bursting due to
osmotic loss/gain of water
buffered: so the pH doesn't fluctuate, so that nothing alters the organelle structures or affects
enzyme functioning
biotic - correct answerliving
capillary structure - correct answerone cell thick endothelium. allows rapid diffusion.
numerous, highly branched, so provides a larger surface area.
narrow lumen and diameter.
spaces in lining to allow tissue fluid to form.
courtship behaviour results in reproductive success by... - correct answer1. allowing recognition
of own species
2. identifying those capable of breeding
3. forming a pair bond
4. synchronising mating
define community - correct answerall the populations of different species living and interacting
in a particular place at the same time.
define ecological niche - correct answerThe position occupied by an organism in a particular
ecosystem, dependent upon the resources it uses. The more resources that are taken into
account then the more carefully defined the organism's niche will be, the organism will become
more specialised.
, define ecology - correct answerthe study of the inter-relationships between organisms and their
environment, including abiotic and biotic factors.
define ecosystem - correct answerdynamic systems made up of a community and all the non-
living factors of its environment. It includes all the living organisms that interact with one
another and also with the physical and non-physical factors present.
define genome - correct answerthe complete set of genes in a cell
define habitat - correct answerthe place where an organism normally lives
define population - correct answera group of individuals that occupy the same habitat at the
same time and are potentially able to interbreed.
define proteome - correct answerthe full range of proteins that a cell is able to produce
describe and explain the countercurrent exchange principle - correct answer-the blood and the
water flow in opposite directions
-blood that is loaded with O2 meets water, which already has maximum O2
-blood with little O2 meets with water with O2 removed
-so, diffusion concentration gradient established and maintained across the entire width of the
gill lamellae
-so, 80% of O2 in water absorbed into fish blood
describe and explain why plant stomata links to gas exchange and its benefits - correct
answerstomata are like minute pores, on the underside of leaves.
each has guard cells, which control the rate of gas exchange
guard cells close when water loss is excessive
A vaccine can be used to produce immunity. Describe how memory cells are important in this
process. (3) - correct answerimportant because when individual is in contact with virus again,
antibodies can be produced at a faster rate in a secondary immune response, and so the
pathogen can be destroyed faster.
abiotic - correct answernon-living
artery structure - correct answerthick muscle layer so that they can dilate and contract to
smooth blood flow.
thick elastic layer so artery can stretch and recoil with systole and diastole, smoothing blood
flow.
overall thickness of wall is large so that it doesn't burst under pressure.
artificial active immunity - correct answerinvolves inducing an immune response in an individual
WITHOUT them suffering the symptoms of the disease.
e.g. vaccinations
memory cells produced
Attaching lactase to the beads is a more efficient use of lactase than adding the lactase
directly to cow's milk.
Suggest three reasons why it is more efficient to attach lactase to the beads. - correct
answerlactase bead can be reused
continuous process
lactase not present in milk
,before cell fractionation, why is the tissue placed in a cold, isotonic buffer? - correct answercold:
reduce enzyme activity that may break down the organelles
isotonic: same water potential as tissue, this prevents organelles shrinking/bursting due to
osmotic loss/gain of water
buffered: so the pH doesn't fluctuate, so that nothing alters the organelle structures or affects
enzyme functioning
biotic - correct answerliving
capillary structure - correct answerone cell thick endothelium. allows rapid diffusion.
numerous, highly branched, so provides a larger surface area.
narrow lumen and diameter.
spaces in lining to allow tissue fluid to form.
courtship behaviour results in reproductive success by... - correct answer1. allowing recognition
of own species
2. identifying those capable of breeding
3. forming a pair bond
4. synchronising mating
define community - correct answerall the populations of different species living and interacting
in a particular place at the same time.
define ecological niche - correct answerThe position occupied by an organism in a particular
ecosystem, dependent upon the resources it uses. The more resources that are taken into
account then the more carefully defined the organism's niche will be, the organism will become
more specialised.
, define ecology - correct answerthe study of the inter-relationships between organisms and their
environment, including abiotic and biotic factors.
define ecosystem - correct answerdynamic systems made up of a community and all the non-
living factors of its environment. It includes all the living organisms that interact with one
another and also with the physical and non-physical factors present.
define genome - correct answerthe complete set of genes in a cell
define habitat - correct answerthe place where an organism normally lives
define population - correct answera group of individuals that occupy the same habitat at the
same time and are potentially able to interbreed.
define proteome - correct answerthe full range of proteins that a cell is able to produce
describe and explain the countercurrent exchange principle - correct answer-the blood and the
water flow in opposite directions
-blood that is loaded with O2 meets water, which already has maximum O2
-blood with little O2 meets with water with O2 removed
-so, diffusion concentration gradient established and maintained across the entire width of the
gill lamellae
-so, 80% of O2 in water absorbed into fish blood
describe and explain why plant stomata links to gas exchange and its benefits - correct
answerstomata are like minute pores, on the underside of leaves.
each has guard cells, which control the rate of gas exchange
guard cells close when water loss is excessive
